Electric heating device for vulcanizing tubes of motorcar or motorcycle tires



Jan. 3, 1939. N, E E 2,142,281

ELECTRIC HEATING DEVICE FOR VULCANIZING TUBES 0F MOTORCAR OR MOTORCYCLE TIRES Filed April 13, 1937 Patented Jan. 3, 1939 ELECTRIC nna'rnve DEVICE Foa vULcAN- rzmc TUBES or MOTOBCAR on MOTOR- CYCLE TIRES Nandor Nmet, Pestujliely, Hungary, assignor of fifty-five per cent to Bella do and forty-five per cent to Bela Vrtyel Vertel, both of Budapest, Hungary Application April 13, 1937, SerialNo. 136,695 I In Hungary September 23, 1936 1Claim.

This invention relates to electric heating devices for vulcanizing India rubber articles and more particularly to devices of the kind provided with a switching device adapted to automatically cut oil the flow of current when a certain temperature is attained and the vulcanizing is finished.

One object of the invention is to construct such a heating device with little dimensions and light weight in order to be able to be easily accommodated in the tool box of motor cars or motor cycles.

Another object of the invention is to reduce the current-consumption of the'device to such a degree that the battery of a motor car, or even of a motor cycle should be a suitable source of current for the device for a period necessary to patch a tube.

Further objects and details of the invention will be understood from the following description having reference to the accompanying drawing.

In the said drawing Fig. 1 is a top plan view of the heating device the cover of which is removed; and Fig. 2 is a cross section taken on line a, b, c,

d, e, These two figures show the device on an enlarged scale.

' Fig. 3 is a top plane view, partly in section, of

the outer casing and the heating body after removal of the switching device, and Fig. 4 a bottom view of the switching device, these two figures showing the invention on natural scale. Fig. 5 is a fragmentary sectional view of the casing of the switching device taken on line 5-5 of Fig. 1.

In the device shown in the drawing by way of example, I denotes an outer casing accommodating an electric heating body 2 and an inner casing 3 containing the automatic switching device and having a bottom of insulating material. The heating body 2 consists, in the embodiment shown, of a wire I (Fig. 3) wound around a ring shaped plate 4 of insulating material and lying between insulating sheets, for instance two mica plates 90. For the sake of simplicity, in Fig. 2 the sections of the parts 4, 4' and 30 areonly diagrammatically shown. The two ends of the wire 4 are connected to contacts 5, and 6 situated above the upper micaplate 39. The whole heating body 2 may be easily removed from casing I, in order to replace it by another one dimensioned for another voltage, if

necessary.

On the bottom of casing 3 there, are contacts 5' and 6' bearing on contacts 5 and 6, and projecting to the inner surface of said bottom, thesecontacts being'not shown in Fig. 2. Contact 5' isperma-f, nently connected to one of a pairof outer con- 55 tacts, which in the embodiment shown are'constituted by plug contacts 29. The other of these plug contacts is in connection with a further, unmovable contact I, which cooperates with a movable contact 8 constituted by a laminated spring. This spring contact is in connection with the said 5 contact 6. On the elastic contact 9 a roller l0 bears, which is mounted on one arm of a switching element 9 pivoted at 2|. The spring 9 tends to leave contact I and a spring l1 bearing on the wall of casing 9 and on switching element 9 also presses the latter in the direction of the arrow 3| shown in Fig. l.

Switching element 9 acts like a two armed lever, the arm ll of which cooperates with a spring controlled locking lever ll swingable around a pin 22. 15 One end of the two armed locking lever l l forms a hook l3 engaging arm I, the other end being fitted with a set screw it. Under this set screw is situated the free end of a bimetallic strip l5 secured at its other end to the bottom of easing 3. 20 If this metal strip is heated, its free end is raised and it engages set screw it. The free space between strip l5 and set screw I9 may be adjusted at will.

The switching element 9 has a projection ll 3| projecting-out of easing 3 through its hole 29 and of casing I through a depression 21 inthe cylindrical wall of this casing I. Projection ll enables the user to swing the element 9 around pivot 2| against the action of springs I and H. A guide 19 prevents arm ll of the switching element from being raised by the nose I! of lever II.

In operation, when a tube is to be patched, the heating device is put in the same place where in the so called Shaller heaters the fuel mass is placed and connection is established with the battery of the car by means of contact plugs 29. Thus the circuitis closed through contacts I, 8, 6', 6, wire 4, contacts 5 and 5'. The temperature of wire 4 is raised in consequence of the electric resistance, so that this 'wire begins to heat the rubber through the bottom of casing l, at the same time heating through a hole 26 of the bottom of easing 3 the bimetallic strip 15. When the desired temperature of about centigrade is attained, strip I5 is bent to such an extent that it raises the left hand end of locking leverl I, against the action of spring l2, so that hook l9 disengages from arm ll, whereupon switching element 9 and contact 8 are moved into the position shown in dotted lines in Fig. 1. Thus the circuit is broken just when the vulcanizing is finished. The sudden jumping out of projection l8 shows to the operator that the vulcanizing is finished.

It is easy to-flnd out the dimensions of heating 55 wire 4 by which after attaining the desired temperature and after breaking the circuit the elapsed period is enough for securing the .patch on the rubber object.

For the next use it is only necessary to push in by a finger projection l8, whereupon contact 8 is pressed to contact 1 and hook or nose I3 01 lever ll snaps behind arm I4 under the action of spring l2.

The hole 26 may be covered by a metal tongue 25 being under the direct action of the heating body 2. The heat is conducted to the bimetallic strip by means of a rivet 20. Furthermore, a protecting plate 32 may be fastened to casing i to avoid injuries of element 9, l8.

Instead of screw I6 on lever H, a set screw 24 (Fig. 1) may be used foradjusting the period of heating. This screw 24 is screwed into a little metalplate 23 which is fastened to the bottom of easing 3. When the metal strip I5 is bent to some extent it reaches screw 24, but in course of further heating the strip is bent further in spite of its engagement with screw 24. The more screw 24 is screwed nearto strip l5, the more it hinders the bending movement and the later the electric circuit of heating wire 6 is broken.

Instead of bimetal l5 any other element known as a thermostat may be employed, which alters its shape under the action of heat.

The described simple, light and reliable construction makes the heater suitable for use on the road for patching tubes. The metal masses of the device being very little, the losses by radiation of heat arealso little, so that the consumption of the device is extremely low.

I claim:

In an electric heating device for vulcanizing rubber tubes, a casing, insulating sheets, an electric resistor situated on the bottom of said casing.

between said insulating sheets, two contacts on the upper insulating sheet for leading current through the resistor, a second casing situated in the said first mentioned casing, two contacts on the outer bottom surface of said second mentioned casing engaging the said two contacts and projecting to the inner bottom surface, an outer contact permanently connected to one of said contacts on the inner bottom surface, a movable spring controlled contact, a further outer contact connected to the other contact on the inner bottom surface by means of said movable spring controlled contact, a movable switching element in the said second casing adapted to close the circuit of said resistor by means of said movable spring controlled contact, a part of said switching element projecting out of both casings for a manual operation, a spring controlled locking lever engaging said switching element when the said circuit is closed,and a bimetallic strip in the said second casing acted upon by said resistor for breaking the said circuit at a certain temperature and a certain period of heating by means of disengaging said locking lever from said switching element.

NA vDoR. NEMET. 

